DJN on "What sorts of topics (NOT SPECIFIC!) to expect on BEC written communication?"

I am studying for BEC and am worried about the WC. From what I've read the topics can come from any area. I'm good with AUD, and will obviously be good with BEC concepts by the exam, but am concerned about being asked questions on FAR or REG areas. Any advice on this?

NOTE: I am not asking anyone for specific topics covered in their WCs, just general info.